What becomes a problem in raising livestock (poultry) is foul odors from livestock and livestock barns, and diseases of the livestock. Most of these foul odors and diseases are brought about by pathogenic bacteria and viruses (hereinafter, properly referred to as “viruses and the like” generically) which are parasitic on excrement and residual food of livestock. Such a foul odor is a serious environmental problem, and the diseases may often become the causes of death and incomplete development of livestock. In fact, death of livestock greatly affects livestock raisers. For example, the death rate of pigs in the pig raising industry sometimes reaches several percent to 20% when it is high. Occurrence of Salmonellosis, Aujeszky disease, PRRS, mycoplasma Pocine Epidemic Diarrhea (PED), Transmissible Gastoenteritis (TGE) and the like tends to increase. In the poultry industry, the news that avian influenza prevailed and a large number of chickens were killed and disposed of is still fresh in our memory. In order to prevent such an event, it is essential to sterilize (disinfect) livestock and the livestock barns to sterilize or inactivate pathogenic bacteria and viruses.
As a method for sterilizing or inactivating such pathogenic bacteria and viruses, Patent Document 1 discloses the method for spraying ozonized water. The ozone concentration of the ozonized water disclosed in the Patent Document 1 is set at 0.05 to 0.10 ppm. However, according to the former Ministry of Health, Labor and Welfare Hygienic Control Laboratory Data (Non-patent Document 1, refer to Table 1), the ozone concentration required for exterminating main microorganisms is about 1 ppm. Accordingly, even if the ozonized water with the ozone concentration being in the above described range is sprayed, a doubt as to its sterilizing effect remains. According to the experiment conducted by Mie Prefectural Science and Technology Promotion Center, Agricultural Technology Center, (Livestock) Small and Medium Livestock Group, it was reported that sprayed ozonized water had no effect of sterilizing Salmonella, more specifically, Salmonella was not able to be sterilized in five minutes after spraying the ozonized water of 1 ppm and 4 ppm (refer to Non-patent Document 2). It is supposed that ozone escaped by spraying. On the other hand, Patent Document 2 discloses the art of spraying ozonized water for disease control. According to the Patent Document 2, the disclosed disease control method is for plants growing in greenhouses, and it poses a question about low-concentration ozonized water similarly as in the above description. Specifically, it finds a question as to practicality in controlling diseases and pest with low-concentration ozonized water, and in the above described disease control method, the ozonized water with an ozone concentration of 2 to 20 ppm is used. Patent Document 2 also describes that on the occasion of spraying high-concentration ozonized water, it is preferable that workers do not enter the greenhouse in which the ozonized water is sprayed. Patent Document 2 does not include the reason why it is preferable, but it is supposed that the case where gas-liquid separation occurs by spraying high-concentration ozonized water, and the ozone generated by the separation increases the ozone concentration in the greenhouse to have an adverse effect on the workers is conceivable, and therefore, Patent Document 2 takes such a case into consideration. In addition to these documents, Patent Document 3 discloses the art of washing horses by producing ozonized water of 2 ppm at the maximum and spraying it.    [Patent Document 1] Japanese Patent Application Laid-open No. 2002-306086 (paragraphs 0012 to 0016)    [Patent Document 2] Japanese Patent Application Laid-open No. 2002-20211 (paragraphs 0006, 0046)    [Patent Document 3] Registered Japanese Utility Model No. 3069986 (paragraphs 0012, 0013, 0016, 0017, FIG. 1)    [Non-patent Document 1] Former Ministry of Health, Labor and Welfare, Hygienic Control Laboratory Data    (http://www.gendaikobo.co.jp/ecogoods/ecogoods01/eogoods01—1.htmL)    [Non-patent Document 2] Title of the Subject of the Study: “Establishment of Salmonella Contamination Prevention Technique for Securing Safety of Poultry Meat/Egg of Local Specialty”    (http://www.affrc.go.jp/ja/db/seika/data_kan-tou/h12/narc00K240.html)
TABLE 1EFFECT OF INACTIVATING MICROORGANISMS BY OZONIZED WATERUNDERWATEROZONEMICROORGANISMDEATHKIND OFCONCENTRATIONCONCENTRATIONTEMPERATURECONTACTRATEMICROORGANISM(ppm)(NUMBER/ml)(° C.)Ph*TIME(%)COLON BACILLUS0.96105 cells2175 SECONDS100STAPHYLOCOCCUS1.08105 cells2175 SECONDS100BACILLUS OF1.01105 cells2175 SECONDS100GREEN PUSCLOSTRIDIUM0.96105 cells2175 SECONDS100PERFRINGENSINFLUENZA VIRUS0.961033 TCID502175 SECONDS100CANINE1.21015 TCID502175 SECONDS100INFECTIOUSHEPATITIS VIRUSCANINE0.961025 TCID502175 SECONDS100PARVOVIRUSAVIAN COCCIDIUM1.923 × 103 cells2075 SECONDS100MOLD0.3-0.5106 cells206.55 SECONDS99.9YEAST0.3-0.5106 cells206.519 SECONDS 99.9BACILLUS SUBTILIS0.3-0.5106 cells206.590 SECONDS 99.9*Ph OF STERILE DISTILLED WATER USED FOR DILUTION TO PREDETERMINED MICROORGANISM CONCENTRATIONMINISTRY OF HEALTH, LABOR AND WELFARE, HYGIENIC CONTROL LABORATORY (PRESENT: NATIONAL INSTITUTE OF INFECTIOUS DISEASE) DATA
However, high-concentration ozonized water has been considered to be incapable of being used for livestock, though it is usable for plants growing in greenhouses. This is because ozone occurring by spraying ozonized water has an adverse effect on livestock. Workers have not been allowed to enter a livestock barn at the time of spraying ozonized water for the same reason. If ozonized water is to be sprayed, it has to be sprayed after livestock is moved to another place to make the livestock barn vacant (all in-all out method), and the workers go outside the livestock barn. However, for an effective use of the space, as much livestock as possible is raised in the livestock barn. Specifically, in most cases, there is no room in the space. It is actually impossible to move the livestock altogether to another place under such a situation. This is the reason why sterilizing of livestock and a livestock barn by ozonized water has not been performed. Further, it can be cited as the reason that sprayed (sprinkled) ozonized water has been believed to have no sterilizing effect as described in the aforementioned Non-patent Document 2.
On the other hand, the art disclosed in Patent Document 3 does not take any measure to ozonized water spraying while there is the technological common sense that Salmonella cannot be sterilized even if ozonized water of 1 ppm and 4 ppm is sprayed as described in the aforementioned Non-patent Document 2. Therefore, according to the art disclosed in Patent Document 3, the ozone concentration after being sprayed cannot be said to be sufficient even when the ozone concentration of the ozonized water at the time when it is produced is 2 ppm at the maximum. Even if the ozone concentration of 2 ppm can be secured after being sprayed, it is extremely difficult to sterilize viruses and the like in the livestock-raising site with the ozonized water of 2 ppm. According to the above described Non-patent Document 1, the ozone concentration required for exterminating main microorganisms is about 1 ppm. However, this result was obtained from the experiment conducted in the test room of the laboratory, and at least 3 ppm which is three times as much as 1 ppm is required in the livestock-raising site. Specifically, microorganisms, viruses or the like in concrete, are parasite on the organic matters such as the excrement of livestock, residual food and the like attached to the body surface of the livestock, and the organic matters also react with ozone. Organic matters float in the air around livestock as dust, and such floating organic matters also the target of reaction with ozone. Sprayed or sprinkled ozonized water reacts with these organic matters immediately when contacting them, and most of it disappears. Therefore, the fact is that the sterilizing effect of ozone does not reach the viruses and the like attached to the livestock bodies.